Validation of a standard forensic anthropology examination protocol by measurement of applicability and reliability on exhumed and archive samples of known biological attribution.
Forensic Sci Int. 2017 Sep 07;279:241-250
Authors: Francisco RA, Evison MP, Costa Junior MLD, Silveira TCP, Secchieri JM, Guimarães MA
Forensic anthropology makes an important contribution to human identification and assessment of the causes and mechanisms of death and body disposal in criminal and civil investigations, including those related to atrocity, disaster and trafficking victim identification. The methods used are comparative, relying on assignment of questioned material to categories observed in standard reference material of known attribution. Reference collections typically originate in Europe and North America, and are not necessarily representative of contemporary global populations. Methods based on them must be validated when applied to novel populations. This study describes the validation of a standardized forensic anthropology examination protocol by application to two contemporary Brazilian skeletal samples of known attribution. One sample (n=90) was collected from exhumations following 7-35 years of burial and the second (n=30) was collected following successful investigations following routine case work. The study presents measurement of (1) the applicability of each of the methods: used and (2) the reliability with which the biographic parameters were assigned in each case. The results are discussed with reference to published assessments of methodological reliability regarding sex, age and-in particular-ancestry estimation.
PMID: 28926780 [PubMed – as supplied by publisher]
Age estimation based on Willems method versus new country-specific method in South African black children.
Int J Legal Med. 2017 Sep 18;:
Authors: Willems G, Lee SS, Uys A, Bernitz H, Cadenas de Llano-Pérula M, Fieuws S, Thevissen P
AIM: The aims of our study were to develop new maturity scores for dental age estimation in South African black children according to the Willems method, which was developed based on Belgian Caucasian (BC) reference data (Willems et al. J Forensic Sci 46(4):893-895, 2001), and to compare age prediction performance of both methods.
SUBJECTS AND METHODS: A total of 986 panoramic radiographs of healthy South African black (SAB) children (493 males and 493 females) in the age range of 4.14 to 14.99 years (mean age 10.06 years) were selected for obtaining developmental staging scores (according to Demirjian et al. Hum Biol 45(2):211-227, 1973). Willems BC methodology was applied to develop new country-specific maturity scores (Willems SAB). Age prediction performance of Willems BC and Willems SAB was compared.
RESULTS: On average, Willems BC renders acceptable results with an overestimation of chronological age of 0.06 years (SD 0.88 years) in SAB children. Compared to Willems SAB, the overall mean absolute error was slightly higher with Willems BC (0.62 and 0.68 years, respectively), but this was not significant in males. Also, the root mean squared error was marginally higher in Willems BC.
CONCLUSION: The new age prediction method developed in South African black children was found to be better compared to Willems BC, although the difference seems to be small and clinically not relevant, especially in males.
PMID: 28921164 [PubMed – as supplied by publisher]
Willems method of dental age estimation in children: A systematic review and meta-analysis.
J Forensic Leg Med. 2017 Aug 25;52:122-129
Authors: Sehrawat JS, Singh M
BACKGROUND: Age estimation from dental developmental stages is considered comparatively more accurate, reliable and precise than other methods used in forensic sciences. Willems method is the revised version of Demirjian method, based on modified dental maturity scores to estimate age of children in years for both the sexes.
AIMS: To test the applicability and accuracy level of Willems method of dental age estimation in diverse population samples by quantifying the variations between the chronological and estimated ages of an individual.
METHODOLOGY: A systematic search of online databases (Pubmed, Scopus, Embase, Medline, Trip and Web of Science) was performed for identifying the articles utilizing Willems dental maturity scaling method for age estimation in children. All the research articles published in peer-reviewed English language journals between 2001 and January 2017 were included for present systematic review and meta-analysis.
RESULTS: Out of the total 973 selected articles; thirty one studies were recruited for qualitative analysis and out of them, 15 studies were selected/identified for quantitative and meta-analysis. It was found that Willems method overestimates the age of children to a comparatively lesser extent (-0.04 and -0.02 years) than the Demirjian method (around six months).
CONCLUSION: Willems method of dental age estimation gives comparatively lesser overestimations of age than other methods reported in the available literature and is thus, accurate and reliable enough to be utilized for forensic purposes.
PMID: 28918371 [PubMed – as supplied by publisher]
Sexual dimorphism in base of skull.
Anthropol Anz. 2017 Apr 01;74(1):9-14
Authors: Amores-Ampuero A
ABSTRACT: Sex determination is an important task in forensic medicine and physical anthropology. The aims of this study were to assess the presence of sexual dimorphism in the base of the skull and to compare the accuracy of sex estimation by this method with that achieved in other metric studies of this region. The sample comprised 109 individuals (53 males and 56 females) of known sex, age, and cause of death from San José cemetery in Granada (Spain). Six dimensions were analyzed and discriminant function analysis was performed. The discriminant capacity of the selected variables was then evaluated by using a cross-validation procedure. All dimensions were significantly higher in males than in females. The percentage accuracy was 75.7% (77.8% for males and 73.7% for females). Highest dimorphic values were for occipital condyle length and foramen magnum width. Skull base measurements should only serve to corroborate findings.
PMID: 28362021 [PubMed – indexed for MEDLINE]
Reliability and validity of five radiographic dental-age estimation methods in a population of Malaysian children.
J Investig Clin Dent. 2016 Feb;7(1):102-9
Authors: Kumaresan R, Cugati N, Chandrasekaran B, Karthikeyan P
OBJECTIVE: To evaluate the reliability and validity of Demirjian’s, Willems, Nolla’s, Haavikko’s, and Cameriere’s radiographic methods of dental-age estimation in a population of Malaysian children.
METHODS: A total of 426 dental panoramic radiographs of 5-15-year-old Malaysian children were included in the study. The mean age error and absolute age error for all the methods were calculated and their usability analyzed.
RESULTS: The Nolla, Willems. and Demirjian methods overestimated the dental age with a mean of 0.97, 0.54, and 0.54 years, respectively, while the Cameriere and Haavikko methods underestimated by 0.41 and 1.31 years, respectively. The Cameriere method was highly precise and accurate in the population of Malaysian children, whereas the Haavikko and Demirjian methods were the least precise and accurate.
CONCLUSIONS: The Cameriere method of dental-age estimation is highly valid and reliable for Malaysian population, followed by the Willems and Nolla methods.
PMID: 25048008 [PubMed – indexed for MEDLINE]
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Sex estimation of the tibia in modern Turkish: A computed tomography study.
Leg Med (Tokyo). 2016 Nov;23:89-94
Authors: Ekizoglu O, Er A, Bozdag M, Akcaoglu M, Can IO, García-Donas JG, Kranioti EF
The utilization of computed tomography is beneficial for the analysis of skeletal remains and it has important advantages for anthropometric studies. The present study investigated morphometry of left tibia using CT images of a contemporary Turkish population. Seven parameters were measured on 203 individuals (124 males and 79 females) within the 19-92-years age group. The first objective of this study was to provide population-specific sex estimation equations for the contemporary Turkish population based on CT images. A second objective was to test the sex estimation formulae on Southern Europeans by Kranioti and Apostol (2015). Univariate discriminant functions resulted in classification accuracy that ranged from 66 to 86%. The best single variable was found to be upper epiphyseal breadth (86%) followed by lower epiphyseal breadth (85%). Multivariate discriminant functions resulted in classification accuracy for cross-validated data ranged from 79 to 86%. Applying the multivariate sex estimation formulae on Southern Europeans (SE) by Kranioti and Apostol in our sample resulted in very high classification accuracy ranging from 81 to 88%. In addition, 35.5-47% of the total Turkish sample is correctly classified with over 95% posterior probability, which is actually higher than the one reported for the original sample (25-43%). We conclude that the tibia is a very useful bone for sex estimation in the contemporary Turkish population. Moreover, our test results support the hypothesis that the SE formulae are sufficient for the contemporary Turkish population and they can be used safely for criminal investigations when posterior probabilities are over 95%.
PMID: 27890111 [PubMed – indexed for MEDLINE]
Investigation of metabolites for estimating blood deposition time.
Int J Legal Med. 2017 Aug 05;:
Authors: Lech K, Liu F, Davies SK, Ackermann K, Ang JE, Middleton B, Revell VL, Raynaud FJ, Hoveijn I, Hut RA, Skene DJ, Kayser M
Trace deposition timing reflects a novel concept in forensic molecular biology involving the use of rhythmic biomarkers for estimating the time within a 24-h day/night cycle a human biological sample was left at the crime scene, which in principle allows verifying a sample donor’s alibi. Previously, we introduced two circadian hormones for trace deposition timing and recently demonstrated that messenger RNA (mRNA) biomarkers significantly improve time prediction accuracy. Here, we investigate the suitability of metabolites measured using a targeted metabolomics approach, for trace deposition timing. Analysis of 171 plasma metabolites collected around the clock at 2-h intervals for 36 h from 12 male participants under controlled laboratory conditions identified 56 metabolites showing statistically significant oscillations, with peak times falling into three day/night time categories: morning/noon, afternoon/evening and night/early morning. Time prediction modelling identified 10 independently contributing metabolite biomarkers, which together achieved prediction accuracies expressed as AUC of 0.81, 0.86 and 0.90 for these three time categories respectively. Combining metabolites with previously established hormone and mRNA biomarkers in time prediction modelling resulted in an improved prediction accuracy reaching AUCs of 0.85, 0.89 and 0.96 respectively. The additional impact of metabolite biomarkers, however, was rather minor as the previously established model with melatonin, cortisol and three mRNA biomarkers achieved AUC values of 0.88, 0.88 and 0.95 for the same three time categories respectively. Nevertheless, the selected metabolites could become practically useful in scenarios where RNA marker information is unavailable such as due to RNA degradation. This is the first metabolomics study investigating circulating metabolites for trace deposition timing, and more work is needed to fully establish their usefulness for this forensic purpose.
PMID: 28780758 [PubMed – as supplied by publisher]
acdc – Automated Contamination Detection and Confidence estimation for single-cell genome data.
BMC Bioinformatics. 2016 Dec 20;17(1):543
Authors: Lux M, Krüger J, Rinke C, Maus I, Schlüter A, Woyke T, Sczyrba A, Hammer B
BACKGROUND: A major obstacle in single-cell sequencing is sample contamination with foreign DNA. To guarantee clean genome assemblies and to prevent the introduction of contamination into public databases, considerable quality control efforts are put into post-sequencing analysis. Contamination screening generally relies on reference-based methods such as database alignment or marker gene search, which limits the set of detectable contaminants to organisms with closely related reference species. As genomic coverage in the tree of life is highly fragmented, there is an urgent need for a reference-free methodology for contaminant identification in sequence data.
RESULTS: We present acdc, a tool specifically developed to aid the quality control process of genomic sequence data. By combining supervised and unsupervised methods, it reliably detects both known and de novo contaminants. First, 16S rRNA gene prediction and the inclusion of ultrafast exact alignment techniques allow sequence classification using existing knowledge from databases. Second, reference-free inspection is enabled by the use of state-of-the-art machine learning techniques that include fast, non-linear dimensionality reduction of oligonucleotide signatures and subsequent clustering algorithms that automatically estimate the number of clusters. The latter also enables the removal of any contaminant, yielding a clean sample. Furthermore, given the data complexity and the ill-posedness of clustering, acdc employs bootstrapping techniques to provide statistically profound confidence values. Tested on a large number of samples from diverse sequencing projects, our software is able to quickly and accurately identify contamination. Results are displayed in an interactive user interface. Acdc can be run from the web as well as a dedicated command line application, which allows easy integration into large sequencing project analysis workflows.
CONCLUSIONS: Acdc can reliably detect contamination in single-cell genome data. In addition to database-driven detection, it complements existing tools by its unsupervised techniques, which allow for the detection of de novo contaminants. Our contribution has the potential to drastically reduce the amount of resources put into these processes, particularly in the context of limited availability of reference species. As single-cell genome data continues to grow rapidly, acdc adds to the toolkit of crucial quality assurance tools.
PMID: 27998267 [PubMed – indexed for MEDLINE]
Development of the Oriental Latrine Fly, Chrysomya megacephala (Diptera: Calliphoridae), at Five Constant Temperatures.
J Med Entomol. 2017 Mar 01;54(2):290-298
Authors: Gruner SV, Slone DH, Capinera JL, Turco MP
Chrysomya megacephala (Fabricius) is a forensically important fly that is found throughout the tropics and subtropics. We calculated the accumulated development time and transition points for each life stage from eclosion to adult emergence at five constant temperatures: 15, 20, 25, 30, and 35 °C. For each transition, the 10th, 50th, and 90th percentiles were calculated with a logistic linear model. The mean transition times and % survivorship were determined directly from the raw laboratory data. Development times of C. megacephala were compared with that of two other closely related species, Chrysomya rufifacies (Macquart) and Phormia regina (Meigen). Ambient and larval mass temperatures were collected from field studies conducted from 2001-2004. Field study data indicated that adult fly activity was reduced at lower ambient temperatures, but once a larval mass was established, heat generation occurred. These development times and durations can be used for estimation of a postmortem interval (PMI).
PMID: 27816915 [PubMed – indexed for MEDLINE]